This invention relates to a non-metallocene catalyst system, consisting of a pyridine-containing metal compound and a suitable activator, which is highly active in the olefin polymerization process.
Polyolefins have been made chiefly using conventional Ziegler catalyst systems, which typically consist of a transition metal halide compound and one or more organoaluminum halide compound. While these catalysts are inexpensive, they suffer from many problems including low activity, staining and instability from residual catalysts, broad molecular distribution, and ineffective co-monomer incorporation. In recent years, the replacement of Ziegler catalysts by metallocene-based systems has begun. Metallocene catalysts, which are transition metal (especially titanium and zirconium) compounds bearing one or more cyclopentadienyl [Cp] ring ligand(s), are typically used with aluminoxanes as activators to give very high activities. Metallocene polyolefin catalysts provide solutions to many of the problems encountered for Ziegler catalysts and are well known in the art.
The commercialization of metallocene catalysts for olefin polymerization has resulted in great interest in the design of non-metallocene homogeneous catalysts. A new generation of catalysts may display superior activity and offer an easier route to known polyolefins and may also lead to processes and products that are outside the capability of metallocene catalysts. In addition, substituted analogues of non-cyclopentadienyl ligands and compounds may be relatively easy to synthesize and hence non-metallocene catalysts may be more economical.
Multidentate anionic oxygen- and nitrogen-based groups have attracted attention as ligands for non-metallocene polyolefin catalysts. In terms of bidentate ligands, pyridinoxy and quinolinoxy ligands have been reported (e.g. U.S. Pat. Nos. 5,637,660, 5,852,146, 6,020,493; Bei et al, Organometallics 1997, 17, 3282; Tshukahara et al, Organometallics 1997, 17, 3303).
A series of tetradentate anionic ligands containing amine-bis(phenolate) groups (phenolate is an aromatic hydroxyl group) have recently been applied in polyolefin catalysts by Kol, Goldschmidt and coworkers (U.S. Pat. No. 6,333,423, Tshuva et al, Chem. Commun. 2000, 379 and Chem. Commun. 2001, 2120). However, these disclosures state that the fourth coordinating moiety or extra donor arm is essential for highly active catalysts, and compounds without the donor arm show poor catalytic activity. In addition, these disclosures focus on the polymerization of 1-hexene, and no information on the polymerization of lower olefins is given. Shao et al (Organometallics 2000, 19, 509) describe zirconium complexes of chelating amine-bis(alkoxide) (alkoxide is an aliphatic hydroxyl group) as polyolefin catalysts, but the observed activity is very low.
Polyolefin catalysts with at least one phenolate group are well known in the art (U.S. Pat. Nos. 4,452,914, 5,079,205). U.S. Pat. Nos. 5,840,646, 6,034,190, EP 0 606 125, and WO 87/02370 disclose bidentate bis(phenolate) titanium and zirconium catalysts for olefin polymerization. Japan Unexamined Patent 6-192330 describes bis(phenolate) plus pyridine-bis(alkoxide) titanium and zirconium catalysts. Further examples of pyridine-bis(alkoxide) groups as ligands in Group 4 metal polyolefin catalysts have been disclosed (JP 9-012582 and Mack et al, J. Chem. Soc. Dalton. Trans. 1998, 917), but the observed activities for the polymerization of ethylene are only moderate.
Hence there is a need in the art for new olefin polymerization catalysts, particularly catalysts containing multidentate ligands of the pyridine-phenolate type. There is also a need in the art for new polyolefin catalysts containing unsymmetric ligands, because this may result in the stereoselective polymerization of 1-olefins (alpha-olefins) and give polyolefins with distinctive morphology and properties.
This invention relates to a polyolefin catalyst system, which comprises a Group 3 to 10 or lanthanide metal (including titanium and zirconium) compound bearing a tridentate pyridine-containing ligand and a suitable activator.
This invention also relates to non-metallocene catalysts of Formula I shown below: 
wherein R1-R11 are each independently selected from a group comprising hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, and substituted heterohydrocarbyl containing 1 to 20 carbon atoms and two or more of the R1-R11 groups may be joined to form cyclic versions; R1-R11 can also be selected from hydrogen, halogen, and recognized donor and acceptor groups; E is a Group 16 element (including oxygen); M is a metal selected from the group comprising Group 3 to Group 10 elements (including titanium and zirconium) and the Lanthanide series elements; m is the oxidation state of the metal; X is a monovalent atom or group bonded to M; Y is a mono- or bidentate molecule datively bound to M, and n is zero or an integer up to five. These catalysts, when combined with a suitable activator, are active for the polymerization of olefins. In instances where R1-R11 are selected such that the tridentate [ENE] ligand is unsymmetric, stereoselective polymerization of 1-olefins can be achieved.